The Sweat Gland Response To Solar Radiation In Three Species Of Domestic Animals

Date

Author

Metadata

Abstract

The present understanding of evaporative
heat loss mechanisms in domestic farm animals.
is based on data gathered from experiments,
carried out in animals exposed to simulated
desert conditions in climatic chambers. Relatively
few experiments have been carried out in the
field, when animals are exposed to the full
natural environmental solar and heat loads.
The quantitative effects of ambient temperature
and solar radiation on sweating rate, body
and skin temperatures were studied in three
species of domestic farm animals: Somali donkey
(Eguus asinus), East African goat (Capra hircus),
and indigenous breeds of cattle, (Bos indicus).
Cutaneous moisture evaporation, skin and
body temperatures were observed in the field
employing a partial shade technique which involved
shading one half of the animal and leaving the
other side exposed to natural environmental
solar and heat loads.
Sweat rates and skin temperature on the
heated and shaded sides of the animals were
compared, using the Van't Hoff's rule and mean Q.lO
values between 205 and 3~5 were obtained. similarly,
2
insensible. water loss 1;(10 values were between
1.2 and 103.
In experiments carried out in the climatic
chamber localized sweating was monitored in response
to a thermal stimulus. From a continuous recording
of cutaneous moisture vaporization (CMY) increases
and decreases in local skin temperature were observed
with corresponding changes in cutaneous moisture
vaporizationo
Differences in field and laboratory values for
CMY were noted. In cattle, for example, CMY values
of 200 g H20/m2• hr. were obtained in the laboratory
compared with field values of 35~ g H20/m20 hr. These
differences can be explained on the basis of a
simple CMY QIO effect
"
The higher CMY values obtained in the field
experiments emphasized the importance of solar
radiation in promoting sweating by acting on the
temperature sensitive sweat gland neuro-effector
junction.